Unopposed estrogen therapy and the risk of invasive breast cancer. Export

@article{citeulike:4883838, abstract = {BACKGROUND: Although short-term unopposed estrogen use does not seem to increase breast cancer risk, the effect of longer-term estrogen use remains unclear. We sought to assess the relationship between longer-term use of unopposed estrogen and the risk of invasive breast cancer over an extended follow-up period. METHODS: Within the Nurses' Health Study, a prospective cohort study, we observed 11 508 postmenopausal women who had a hysterectomy and reported information on estrogen use at baseline (1980). The study population was expanded every 2 years to include women who subsequently became postmenopausal and had a hysterectomy, so that 28 835 women were included in the final follow-up period (2000-2002). Estrogen use was assessed from self-reported data on biennial questionnaires. The main outcome was invasive breast cancer. RESULTS: A total of 934 invasive breast cancers were included in the analysis. Breast cancer risk increased with duration of unopposed estrogen use among longer-term users with the highest risk seen in cancers positive for estrogen receptor (ER+) and progesterone receptor (PR+). The multivariate relative risks (RRs) and 95\% confidence intervals (CIs) for breast cancer with current use of unopposed estrogen for less than 5 years, 5 to 9.9 years, 10 to 14.9 years, 15 to 19.9 years, and 20 years or longer were, respectively, 0.96 (95\% CI, 0.75-1.22), 0.90 (95\% CI, 0.73-1.12), 1.06 (95\% CI, 0.87-1.30), 1.18 (95\% CI, 0.95-1.48), and 1.42 (95\% CI, 1.13-1.77) (P for trend <.001). The risk of ER+/PR+ breast cancers was noted to be statistically significant after 15 years of current use (RR, 1.48; 95\% CI, 1.05-2.07). CONCLUSION: Users of unopposed estrogen were at increased risk of breast cancer but only after longer-term use.}, author = {Chen, W. Y. and Manson, J. E. and Hankinson, S. E. and Rosner, B. and Holmes, M. D. and Willett, W. C. and Colditz, G. A.}, citeulike-article-id = {4883838}, citeulike-linkout-0 = {http://dx.doi.org/10.1001/archinte.166.9.1027}, citeulike-linkout-1 = {http://view.ncbi.nlm.nih.gov/pubmed/16682578}, citeulike-linkout-2 = {http://www.hubmed.org/display.cgi?uids=16682578}, day = {8}, doi = {10.1001/archinte.166.9.1027}, issn = {0003-9926}, journal = {Archives of internal medicine}, keywords = {aggressiveness, breast, cancer, hrt, superlist, thelist}, month = {May}, number = {9}, pages = {1027--1032}, posted-at = {2009-06-17 21:09:54}, priority = {2}, title = {Unopposed estrogen therapy and the risk of invasive breast cancer.}, url = {http://dx.doi.org/10.1001/archinte.166.9.1027}, volume = {166}, year = {2006} }

TY - JOUR ID - citeulike:4883838 L3 - citeulike-article-id:4883838 N2 - BACKGROUND: Although short-term unopposed estrogen use does not seem to increase breast cancer risk, the effect of longer-term estrogen use remains unclear. We sought to assess the relationship between longer-term use of unopposed estrogen and the risk of invasive breast cancer over an extended follow-up period. METHODS: Within the Nurses' Health Study, a prospective cohort study, we observed 11 508 postmenopausal women who had a hysterectomy and reported information on estrogen use at baseline (1980). The study population was expanded every 2 years to include women who subsequently became postmenopausal and had a hysterectomy, so that 28 835 women were included in the final follow-up period (2000-2002). Estrogen use was assessed from self-reported data on biennial questionnaires. The main outcome was invasive breast cancer. RESULTS: A total of 934 invasive breast cancers were included in the analysis. Breast cancer risk increased with duration of unopposed estrogen use among longer-term users with the highest risk seen in cancers positive for estrogen receptor (ER+) and progesterone receptor (PR+). The multivariate relative risks (RRs) and 95% confidence intervals (CIs) for breast cancer with current use of unopposed estrogen for less than 5 years, 5 to 9.9 years, 10 to 14.9 years, 15 to 19.9 years, and 20 years or longer were, respectively, 0.96 (95% CI, 0.75-1.22), 0.90 (95% CI, 0.73-1.12), 1.06 (95% CI, 0.87-1.30), 1.18 (95% CI, 0.95-1.48), and 1.42 (95% CI, 1.13-1.77) (P for trend <.001). The risk of ER+/PR+ breast cancers was noted to be statistically significant after 15 years of current use (RR, 1.48; 95% CI, 1.05-2.07). CONCLUSION: Users of unopposed estrogen were at increased risk of breast cancer but only after longer-term use. IS - 9 JF - Archives of internal medicine SN - 0003-9926 EP - 1032 TI - Unopposed estrogen therapy and the risk of invasive breast cancer. VL - 166 SP - 1027 KW - aggressiveness KW - breast KW - cancer KW - hrt KW - superlist KW - thelist AU - Chen, WY AU - Manson, JE AU - Hankinson, SE AU - Rosner, B AU - Holmes, MD AU - Willett, WC AU - Colditz, GA PY - 2006/05/08/ UR - http://dx.doi.org/10.1001/archinte.166.9.1027 ER -